[PATCH v4 3/6] pseries/plpks: expose PowerVM wrapping features via the sysfs

Srish Srinivasan
2026-01-15T11:57:32Z

Starting with Power11, PowerVM supports a new feature called "Key Wrapping"
that protects user secrets by wrapping them using a hypervisor generated
wrapping key. The status of this feature can be read by the
H_PKS_GET_CONFIG HCALL.

Expose the Power LPAR Platform KeyStore (PLPKS) wrapping features config
via the sysfs file /sys/firmware/plpks/config/wrapping_features.

Signed-off-by: Srish Srinivasan <ssrish@linux.ibm.com>
---
.../ABI/testing/sysfs-firmware-plpks | 8 ++++++++
arch/powerpc/include/asm/hvcall.h | 4 +++-
arch/powerpc/include/asm/plpks.h | 3 +++
arch/powerpc/platforms/pseries/plpks-sysfs.c | 2 ++
arch/powerpc/platforms/pseries/plpks.c | 20 +++++++++++++++++++
5 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-firmware-plpks b/Documentation/ABI/testing/sysfs-firmware-plpks
index af0353f34115..cba061e4eee2 100644
--- a/Documentation/ABI/testing/sysfs-firmware-plpks
+++ b/Documentation/ABI/testing/sysfs-firmware-plpks
@@ -48,3 +48,11 @@ Description: Bitmask of flags indicating which algorithms the hypervisor
supports for signed update of objects, represented as a 16 byte
hexadecimal ASCII string. Consult the hypervisor documentation
for what these flags mean.
+
+What: /sys/firmware/plpks/config/wrapping_features
+Date: November 2025
+Contact: Srish Srinivasan <ssrish@linux.ibm.com>
+Description: Bitmask of the wrapping features indicating the wrapping
+ algorithms that are supported for the H_PKS_WRAP_OBJECT requests
+ , represented as a 8 byte hexadecimal ASCII string. Consult the
+ hypervisor documentation for what these flags mean.
diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index 9aef16149d92..dff90a7d7f70 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -360,7 +360,9 @@
#define H_GUEST_RUN_VCPU 0x480
#define H_GUEST_COPY_MEMORY 0x484
#define H_GUEST_DELETE 0x488
-#define MAX_HCALL_OPCODE H_GUEST_DELETE
+#define H_PKS_WRAP_OBJECT 0x490
+#define H_PKS_UNWRAP_OBJECT 0x494
+#define MAX_HCALL_OPCODE H_PKS_UNWRAP_OBJECT

/* Scope args for H_SCM_UNBIND_ALL */
#define H_UNBIND_SCOPE_ALL (0x1)
diff --git a/arch/powerpc/include/asm/plpks.h b/arch/powerpc/include/asm/plpks.h
index 8829a13bfda0..8f034588fdf7 100644
--- a/arch/powerpc/include/asm/plpks.h
+++ b/arch/powerpc/include/asm/plpks.h
@@ -23,6 +23,7 @@
#define PLPKS_IMMUTABLE PPC_BIT32(5) // Once written, object cannot be removed
#define PLPKS_TRANSIENT PPC_BIT32(6) // Object does not persist through reboot
#define PLPKS_SIGNEDUPDATE PPC_BIT32(7) // Object can only be modified by signed updates
+#define PLPKS_WRAPPINGKEY PPC_BIT32(8) // Object contains a wrapping key
#define PLPKS_HVPROVISIONED PPC_BIT32(28) // Hypervisor has provisioned this object

// Signature algorithm flags from signed_update_algorithms
@@ -103,6 +104,8 @@ u32 plpks_get_maxlargeobjectsize(void);

u64 plpks_get_signedupdatealgorithms(void);

+u64 plpks_get_wrappingfeatures(void);
+
u16 plpks_get_passwordlen(void);

void plpks_early_init_devtree(void);
diff --git a/arch/powerpc/platforms/pseries/plpks-sysfs.c b/arch/powerpc/platforms/pseries/plpks-sysfs.c
index 01d526185783..c2ebcbb41ae3 100644
--- a/arch/powerpc/platforms/pseries/plpks-sysfs.c
+++ b/arch/powerpc/platforms/pseries/plpks-sysfs.c
@@ -30,6 +30,7 @@ PLPKS_CONFIG_ATTR(used_space, "%u\n", plpks_get_usedspace);
PLPKS_CONFIG_ATTR(supported_policies, "%08x\n", plpks_get_supportedpolicies);
PLPKS_CONFIG_ATTR(signed_update_algorithms, "%016llx\n",
plpks_get_signedupdatealgorithms);
+PLPKS_CONFIG_ATTR(wrapping_features, "%016llx\n", plpks_get_wrappingfeatures);

static const struct attribute *config_attrs[] = {
&attr_version.attr,
@@ -38,6 +39,7 @@ static const struct attribute *config_attrs[] = {
&attr_used_space.attr,
&attr_supported_policies.attr,
&attr_signed_update_algorithms.attr,
+ &attr_wrapping_features.attr,
NULL,
};

diff --git a/arch/powerpc/platforms/pseries/plpks.c b/arch/powerpc/platforms/pseries/plpks.c
index 03722fabf9c3..4a08f51537c8 100644
--- a/arch/powerpc/platforms/pseries/plpks.c
+++ b/arch/powerpc/platforms/pseries/plpks.c
@@ -38,6 +38,7 @@ static u32 usedspace;
static u32 supportedpolicies;
static u32 maxlargeobjectsize;
static u64 signedupdatealgorithms;
+static u64 wrappingfeatures;

struct plpks_auth {
u8 version;
@@ -248,6 +249,7 @@ static int _plpks_get_config(void)
__be32 supportedpolicies;
__be32 maxlargeobjectsize;
__be64 signedupdatealgorithms;
+ __be64 wrappingfeatures;
u8 rsvd1[476];
} __packed * config;
size_t size;
@@ -280,6 +282,7 @@ static int _plpks_get_config(void)
supportedpolicies = be32_to_cpu(config->supportedpolicies);
maxlargeobjectsize = be32_to_cpu(config->maxlargeobjectsize);
signedupdatealgorithms = be64_to_cpu(config->signedupdatealgorithms);
+ wrappingfeatures = be64_to_cpu(config->wrappingfeatures);

// Validate that the numbers we get back match the requirements of the spec
if (maxpwsize < 32) {
@@ -472,6 +475,23 @@ u64 plpks_get_signedupdatealgorithms(void)
return signedupdatealgorithms;
}

+/**
+ * plpks_get_wrappingfeatures() - Returns a bitmask of the wrapping features
+ * supported by the hypervisor.
+ *
+ * Successful execution of the H_PKS_GET_CONFIG HCALL during initialization
+ * reads a bitmask of the wrapping features supported by the hypervisor into the
+ * file local static wrappingfeatures variable. This is valid only when the
+ * PLPKS config structure version >= 3.
+ *
+ * Return:
+ * bitmask of the wrapping features supported by the hypervisor
+ */
+u64 plpks_get_wrappingfeatures(void)
+{
+ return wrappingfeatures;
+}
+
/**
* plpks_get_passwordlen() - Get the length of the PLPKS password in bytes.
*
--
2.47.3